1. Field of the Invention
The present invention relates to a gas polishing apparatus having a gas nozzle device to produce a flat surface by removing surface structures on a workpiece such as semiconductor wafer using a reactive gas, or conversely, to fabricate a given surface structure on the work surface.
2. Description of the Related Art
As the density of circuit integration in semiconductor devices becomes ever higher, circuit patterns are becoming finer and interline spacing narrower. Accompanying this trend, the depth of focus become very shallow in photolithographic reproduction of circuit patterns, and it requires that the surface of the wafer placed at the focal plane of a stepper must be microscopically flat to produce the required degree of image sharpness.
A method of producing such a flat surface on a wafer is known as a chemical mechanical polishing (CMP) in which a work surface of a wafer which is held in a wafer holding device is pressed and rotated against an abrading surface of a polishing table while supplying a polishing solution at the abrading interface.
However, the CMP process is designed to produce flatness by polishing the entire surface of a wafer as a whole, and therefore, it is not suitable for removing macroscopic surface irregularities, such as those shown in FIG. 25, and results in removal of much quantity of material and is thus time-consuming.